FR2719006A1 - Anti-theft device for motor vehicle. - Google Patents

Abstract

Anti-theft device for motor vehicles comprising a switch (11) located between the power supply lead (8, 9) of at least one of the units needed to operate or start up the vehicle engine, the closure of said switch being controlled by a control circuit (12) activated in response to the reception of a code signal provided by a transmitter (15) connected to the control circuit (12) by said power supply lead (8, 9).

Description

The invention relates to an anti-theft device for

motor vehicles.

  In the field of the fight against the theft of motor vehicles it is essentially a question of delaying the action of the thief. The devices which are experiencing the greatest development today are those which put at least one of the essential parts of the vehicle out of service and which can only be restored to service with a specific accessory held only by a person authorized. These decommissioning and restorations are generally obtained by circuit breakers

  power supply controlled by electro- circuits

  nics activated by code keys (optical transmitter, magnetic or chip card, dongles ...). Their installation is generally separate from all the electrical cables of a

  vehicle so that these devices are easily identified

  reliable and identifiable; it is then possible to short them--

  circuit fairly easily when you have access to space

vehicle engine.

  The present invention intends to remedy this drawback by proposing an anti-theft system which does not

  in separate wiring harnesses from the original cable bundles

  gine the vehicle so that its detection is much more difficult. In addition, its installation, even in recovery after

  vehicle construction is simplified.

  More specifically, the subject of the invention is an anti-theft device for a motor vehicle which comprises a

  switch inserted on the power supply conductor

  that at least one of the organs essential for the operation or starting of the vehicle engine, with closure controlled by a control circuit activated in response to the reception of a coded signal generated by a transmitter connected to the

  control by said supply conductor.

  The supply conductor thus constitutes a signal carrying line which makes it possible to close the switch.

  and thus restore the organ to its working state-

  ment, that is to say capable of being supplied with electricity-

  is lying. In one embodiment, the control circuit comprises a relay for actuating the switch, the power supply of which is established by means of a receiving microcontroller after the latter has recognized the coded signal from a capacitance d accumulation of charged energy at

  time of transmission of the coded signal. So when

  of the coded signal, the transmitting microcontroller also emits a sufficient amount of energy to charge a capacity capable of maintaining the excitation of the relay.

  closing of the switch which reconstitutes the conti-

  nakedness of the organ supply line.

  Preferably, in order to ensure engine operating safety, the control circuit includes a switch with self-holding relay in

  bypass on the controlled closing switch.

  Furthermore, the coded signal transmitter comprises an electronic microcontroller activated by a coded key when the key is connected to the microcontroller and its code recognized by comparison with one of the codes which the transmitting microcontroller has in memory. , an output of this micro-controller being connected to the supply conductor downstream of a switch of this conductor for transmitting the signal

  coded to the device to which it is connected.

  Other characteristics and advantages of the invention

  tion will emerge from the description given below of a

example of realization.

  Reference will be made to the appended drawings in which: - Figure 1 is a general diagram of the device according to the invention, - Figure 2 is a diagram of a variant of

realization of figure 1.

  In FIG. 1, line 1 represents the general electrical supply line for a motor vehicle engine. In known manner, this line comprises a general switch 2 actuated by a key 3 which in a first position closes a general contactor 4 and in a

  second position closes a second contact 5 for the temporary excitation of a relay 6 associated with a contactor 7 for the electrical supply of a motor (not shown) for starting the vehicle.

  Downstream of the main switch 2, line 1 is divided into several conductors 8, 9 intended to supply the

  various electrical components of vehicles. Line 8 is that for example assigned to the starter, while line 9 can be that assigned to the supply of the ignition members.

  According to the invention, each or at least one of the conductors 8, 9, is equipped with a cut-off device 10 whose function is to keep this conductor 8, 9 interrupted as long as, before contact 4 is closed, there is no 'has not received coded information authorizing the restoration of the continuity of the conductor 8, 9. This device 10 essentially comprises a switch 11, normally open, an electronic circuit for controlling the closing of this

  switch 11, and a contactor 13 with auto relay

  hold bypass on switch 11.

  According to the invention also, the electronic circuit

  control switch 11 is connected to a device

  tif transmitter 14 of a coded signal via conductors 8, 9 and the general supply line 1

downstream of the main switch 2.

  More specifically, the transmitter device 14 comprises a transmitter microcontroller 15, the power supply of which is supplied by the battery of the vehicle from which the general supply line 1 comes and which

  includes, in addition to the central processing unit,

  mée, external contacts 16 for reading a memory 17 carried by an external key 18 in the form of a card

  chip or electronic key, a keyboard 19 for programming

  tion of the operating modes of the microcontroller and of the indicators 20 and 21 for displaying the status in order of

  on or out of order for the entire installation

  tion of the vehicle controlled by the device of the invention. The microcontroller also includes an electrically programmable memory 22 in which three reference information items A, B and C are housed. At the output, the microcontroller 15 is connected to the supply line

  general 1, downstream of general contactor 2, by a conduc-

  tor 23, by means of which it can inject a coded signal into

  the entire electrical installation of the vehicle.

  The electronic circuit for controlling the interrup-

  tor 11 of each switching device 10 also comprises a receiving microcontroller 24, the power supply of which is ensured by a capacitor 25, this microcontroller 24 having an input 26 connected to the part of the conductor 8 from the general line 1 and an output 27 for controlling the supply of a relay 28 associated with the switch 11. The microcontroller 24 also includes an electrically erasable and programmable memory 29, which each contains reference codes A, B, C. On will notice that installing the device

  according to the invention on an existing vehicle consists simply-

  ment to connect the power supply of the microcontroller 15 to the vehicle battery, to connect the conductor 23 downstream of the general contactor 2 on line 1, and to interrupt each of the supply conductors 8, 9 of the various essential organs of the vehicle, or at least one of them to insert

  in series on this conductor each of the devices 10.

  Advantageously, each of the devices 10 will be constituted by electronic components so that the switches will be static switches and will be enclosed in a box or embedded in a resin of generally cylindrical exterior shape whose diameter will be such that its insertion into a bundle general does not significantly change the shape of this beam. This device will therefore be difficult to locate and detect. The memories 22, 29 of each microcontroller 15

  and 24 are responsible for the codes A, B, C which personalize it.

  With the device three keys 18 are delivered, each of them having one of the codes A, B, C recorded in its memory 17. In the standby state, the microcontroller 15 excites

  one of the indicators 20 (for example a light emitting diode-

  red cent) indicating that the vehicle is in its muting state. Furthermore, the microcontroller 15 is, by default, in its operating mode called "starting the

  vehicle ". Its other operating mode called" program-

  tion "can be established by pressing the P key on the keyboard 19. The vehicle user inserts his key 18 at the place provided for this purpose to establish contact between the microcontroller 15 and the memory 17. This action launches the operating sequence of the microcontroller 15 which checks the coincidence between the information carried by the memory 17

  and one of the pieces of information A, B, C stored in its memory 22.

  When this coincidence is established, the microcontroller 15 emits a coded signal on the conductor 23 towards each of the cut-off devices 10 of the installation via the electrical lines and conductors 1, 8, 9. This coded signal comprises first a relatively long first pulse which has the function of charging the capacitors 25, these then being in a state to supply each of the microcontrollers 24 of each device 10. This pulse is followed by a

  coded signal received by input 26 from each of the micro-controllers

  their reception 24 which corresponds to one of the codes A, B,

  C contained in memory 23 of each microcontroller.

  After a sequence of comparison and verification of the

  signal with one of these stored codes, the micro-control

  their receiver 24 supplies via its output 27 the relay 28 which closes the contactor 11. This closing state is maintained

  for a time of the order of 10 to 20 seconds, and the micro-

  controller 15 in return controls the supply of the indicator light 21 (for example a green light-emitting diode) indicating to the user that the vehicle is in a state of being able to be started. At this time, by the key 3 for closing the general contactor, the contact 4 is closed and each of the self-holding contactors 13 is also closed. Contact is therefore established and the vehicle's electrical components are energized. The excitation of the relays 28 can cease causing the opening of the switches 11 without, however, cutting off the power to the components of the vehicle. The user can then, for example, start his vehicle by acting again on the key 3 to close the contact 5, which causes the electric starter motor to be powered.

of this vehicle.

  In the absence of a key 18 or in the presence of a key 18 which does not have one of the three codes A, B, C to be recognized, the relays 28 are not supplied and the switches 11 remain open. The actuation of the ignition key 3 then produces no effect on the vehicle components. His

  startup is thus completely inhibited.

  When the vehicle stops, the opening of the general contact causes all of the self-maintained contactors 13 to open. The owner of the vehicle equipped with the device according to the invention has three keys 18 each having one of the codes A, B, C in memory. If one of the keys is lost, it can be replaced by another key. So that this new key can be recognized by the system,

  the microcontroller 15 has another operating mode

  ment which can be selected by pressing the P key on the keyboard 19. Under these conditions, the procedure can be as follows: successively, the contacts are introduced

  16 the two keys whose codes are known to micro-

  controllers 15 and 24, this operation generating a processing sequence in the microcontrollers 15 and 24 such that the latter are capable of reading the code contained in the new key and of writing it in each of the memories 22 and 29 at the address of the lost key code. At the end of this sequence, the microcontroller 15 returns by default to its current operating mode. This procedure makes it possible to remove any provision in the device which would allow copying a key capable of operating it in order to constitute one or more backup duplicates. We know that any possible or permitted copy involves the possibility of fraud. The invention thus makes it possible to have three original keys which cannot be copied while, in spite of everything, making it possible to remedy the risk of loss or theft of a key. The "validation" of a new key makes the lost or stolen key inoperative. This provision may have an advantage, in particular with regard to vehicles intended for rental. Indeed, we can thus change the code for

  each new user of the vehicle.

  In FIG. 2, the variant of the invention represents

  Tee consists in replacing the general switch 2 known in itself by a switch 30 controlled by a relay 31 whose power depends on the micro-controller 15, this switch 30 can be doubled bypass by a self-holding switch 32 while the key 18 performs the function of general contactor 33 and contactor 34 of the starter. This variant eliminates the generally known general contactors which generally provide mechanical locking of the steering column. This

  removal reduces the risk of vandalism and damage

  ration by the thief who usually forces the lock

  steering column mechanics.

  In the embodiments described above, the signal

  coded injected into conductors 1, 8 and 9 by the micro-

  controller 15 is in direct relation with the key which causes its emission. This provision implies having

  in each of the microcontrollers 24 of the codes of each key.

  It is then possible, by additional data processing, to classify certain data specific to the

  driving the vehicle according to the key holder.

  In a simpler version of the invention, the coded signal can be unique whatever the key that generates it. In this case the microcontrollers 24 are programmed to recognize this unique signal which can also be unique whatever the device or on the contrary different from one device to another and this by initial programming.

Claims (7)

  1. Anti-theft device for a motor vehicle, characterized in that it comprises a switch (11) inserted on the electrical supply conductor (8, 9) of at least one of the organs essential for the operation or starting of the engine of the vehicle, closing controlled by a control circuit (12) activated in response to the reception of a coded signal generated by a transmitter (15) connected to the circuit   control (12) by said supply conductor (8, 9).   2. Device according to claim 1, characterized in that the control circuit (12) comprises a relay (28) for actuating the switch (11), the supply of which is established by means of a microcontroller ( 24) receiver, after recognition by the latter of the coded signal, from a capacity (25) for accumulating charged energy at the time of the transmission of the coded signal.   3. Device according to claim 2, characterized   in that the control circuit (12) comprises an interrup-   tor (13) with self-hold relay on bypass   the switch (11) with controlled closure.   4. Device according to one of the preceding claims, characterized in that the coded signal transmitter   comprises an electronic microcontroller (15) activated by an encoded key (17) when the key is connected to the microcontroller and its code recognized by comparison with one of the codes (A, B, C) which comprises in memory (22) the transmitting microcontroller (15), an output (23) of the microcontroller being connected to the supply conductor (8, 9) downstream of a switch (2, 30) of this conductor, to transmit the   coded signal to each of the receiver control circuits (12).   5. Device according to claim 4, characterized in that the closing of the switch (30) of the supply conductor (1) is ensured by a relay (31) whose supply circuit is closed by the microcontroller   transmitter (15) in a sequence following that of recognition   sance of the key (17) for transmitting the coded signal.   6. Device according to one of the preceding claims, characterized in that the microcontroller   transmitter (15) comprises three stored codes (A, B, C) of reference for three keys (18), each code being housed in a memory (22) reprogrammable by means of a procedure   implementing the successive recognition of the codes of two coded keys (18). 7. Device according to one of claims   previous, characterized in that the switch (11) and the control circuit (12) associated with each essential member are arranged in a cylindrical housing capable of being housed   in a substantially cylindrical bundle of conductors.